South Korean President Moon Jae-in’s special envoys to North Korea have no plans to discuss the release of South Koreans and Americans detained in the communist state just yet, the presidential office said Monday.

“I cannot be 100 percent certain that the matter will not be discussed, but it is not an agenda item (for the special envoys to North Korea,)” an official from the presidential office told reporters on condition of anonymity. “The core of preliminary talks between North Korea and the US is denuclearization.

It is not yet in the stage to discuss such details as the release of South Korean and American detainees in the North, and the purpose of the envoys’ visit is to primarily help the US and North Korea sit down for talks, the official added.

Otto Warmbier (Yonhap)

His remarks came after local media outlets reported that Moon’s special envoys would discuss the release of three American detainees there during their two-day trip to Pyongyang and the envoys would brief US officials on the result of their discussion with the North to give both countries ground to start a dialogue.

Headed by the National Security Office Chief Chung Eui-yong, the five-member delegation departed for North Korea on Monday mainly to convince the reclusive regime to hold talks with the US on its nuclear weapons programs and discuss ways to improve inter-Korean ties.

Three American citizens and six South Koreans remain in captivity in North Korea.

Among them is Kim Dong-chul, a Korean-American missionary who was arrested on Oct. 2, 2015. He had lived in Yangji, China, and worked as head of a hotel services company in a special economic zone in the North since 2001. Kim was made to appear at a news conference held in Pyongyang on March 25, 2015, where he confessed to “espionage activities under South Korea’s instruction in systemically gathering secrets of the North Korea’s party, state and military and handing them over to the South.” He has served 10 years of hard labor since 2006.

Tony Kim, also known as Kim Sang-duk, was arrested for “hostile acts” against the Kim Jong-un regime at Pyongyang Airport on April 21 last year as he was leaving the country. He was in North Korea teaching accounting at Pyongyang University of Science and Technology as a visiting professor. Kim, who formerly taught at Yanbian University of Science and Technology, had been engaged in humanitarian work inside the impoverished country.

Kim’s son asked for help to bring his father home in a YouTube video in February ahead of the PyeongChang Olympics. The appeal for help came amid a rare diplomatic breakthrough on the Korean Peninsula with the North’s participation in the Winter Games.

Chinese-born Korean Kim Hak-song was detained in the North on May 7 last year. He was arrested at Pyongyang Station while waiting for a train bound for his hometown of Dandong, China. He studied theology in Los Angeles and obtained US citizenship in 2008. He had worked at Pyongyang University of Science and Technology since 2014.

Joseph Yun, then-US special representative for North Korea policy, was able to meet with the American detainees in June last year when he went to North Korea to bring Otto Warmbier, a US student who died days after being released from North Korea, according to State Department. But there has been no progress in talks over release of the detainees in the North.

While exact data are not available, six South Koreans are believed to be held in the North, according to the Unification Ministry. They include evangelical missionaries Kim Jung-wook, Kim Kuk-ki and Choi Chun-gil, who were detained in October 2013, October 2014, and in December 2014, respectively. The three are believed to be serving life imprisonment of hard labor. The other three are thought to be North Korean defectors who obtained South Korean citizenship.

“As for South Korean citizens detained in North Korea, the government is trying to release them through diplomatic channels and striving to receive the support of the international community for that,” an official from the Foreign Ministry said on condition of anonymity. “We will continue to try though there has not yet been a progress.”

The National Human Rights Commission of Korea sent a letter to United Nations Secretary-General Antonio Guterres in December last year, asking the UN to open an investigation into the condition of the six South Koreans detained in the North.

The NHRCK said it had also filed a petition to the Special Rapporteur on human rights in North Korea, the Working Group on Arbitrary Detention and the Working Group on Enforced or Involuntary Disappearances, asking them to look into the situation of the Korean detainees in the North.